. Botany for agricultural students . Botany. 402 THALU)PHYTES disease on the leaves and fruit. Upon the Apple tree, the aecidia stage is produced, and the aecidiospores are able to attack the Cedar and form new galls, thus completing the life cycle as shown in Figure 361. Pine Tree Blister-rust (Cronartium ribicola). — As its name suggests this Rust attacks Pine trees. It was introduced from Europe about ten years ago and has now become a seri- ous disease in this country. It has its aecidial stage on Pines with five leaves in a fascicle, such as the White Pine and Sugar Pine, and has species
. Botany for agricultural students . Botany. 402 THALU)PHYTES disease on the leaves and fruit. Upon the Apple tree, the aecidia stage is produced, and the aecidiospores are able to attack the Cedar and form new galls, thus completing the life cycle as shown in Figure 361. Pine Tree Blister-rust (Cronartium ribicola). — As its name suggests this Rust attacks Pine trees. It was introduced from Europe about ten years ago and has now become a seri- ous disease in this country. It has its aecidial stage on Pines with five leaves in a fascicle, such as the White Pine and Sugar Pine, and has species of Ribes (Goose- berries and Currants) as the other host. In this Rust the aecidial stage is the most de- structive. The mycelium of the aecidial stage kills the cambium and inner bark of Pines, thus causing the death of branches and some- times of the entire tree. Both uredospores and teleu- tospores are produced on the infected Currant and Gooseberry bushes, which are apparently very little injured thereby. Pines are infected through the basid- iospores. The chief means of checking the spread of the disease is through the destruction of the wild Currant and Gooseberry bushes. The damage done to Pine trees is serious and since our Pine forests are valued at many, millions of dollars, it is not surprising that our government has put restrictions upon the importation of Pines from Europe and has appro- priated large sums of money to be expended in checking this Fig. 360. — A Cedar Apple whicli has developed the gelatinoiis branches con- taining numerous teleutospores. The teleutospores produce sporidia or basidio- spores that attack the Apple tree. These gelatinous branches develop in the spring after a rain and while the leaves and shoots of the Apple are young and easily attacked. After Bulletin 257, Wisconsin Agr. Exp. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
